C.O.R.N. Newsletter: 2022-12
-
Springtime is Spray Time -- Here are Some Tips for Better Spraying
Applying pesticides requires a high level of skill and knowledge. Increases in the size and complexity of sprayers over the years require even more attention to efficiency, efficacy, and safety. Although each crop requires a slightly different approach to the application of pesticides, some general principles apply to almost all spraying situations. Here are my top 10 recommendations (not in a particular order) that will make spraying efficient and effective resulting in a higher level of biological efficacy expected from pesticides applied:
- Select the best nozzle type and size for the job. Although each component of the sprayer plays a role in achieving success in pesticide application, nozzles play the most significant role. Nozzles come in a wide variety of types and sizes. Each type is designed for a specific target and application. Most manufacturers’ catalogs and websites have charts showing which nozzle type is best for a specific job. Any of the following factors may be the deciding one when selecting the most appropriate nozzle for the job: Sprayer operation parameters (application rate, spray pressure, ground speed); the type of chemicals applied (herbicide, insecticide, fungicide, fertilizers); mode of action of the chemical (systemic or contact) for spray coverage requirement; application type (broadcast, band, directed, air-assisted); risk of spray drift; and specific nozzle or droplet size requirement given on the product label. Once you determine the best nozzle that will be best for a specific spraying situation, you need to determine the appropriate size of that nozzle that provides the application rates (gal / acre) prescribed by product labels under various operating conditions (spray pressures and travel speeds). More information on selecting nozzle type and size is outlined in Ohio State University (OSU) Extension publication FABE-528, “Selecting the Best Nozzle for the Job.” (ohioline.osu.edu/factsheet/fabe-528).
- Carefully read and follow the specific recommendations provided in sprayer operator’s manuals and labels of pesticides applied. Remember, what is required in a label is the law. For example, the labels of 2,4-D or Dicamba herbicides include specific requirements for nozzles and operating pressure ranges. If you use any other type and size of nozzle and operate them outside the pressure range requirements given by the pesticide manufacturers, you are violating the pesticide label, and therefore the law. Remember, the label is the law!
- Keep spray drift in mind when spraying. Although complete elimination of spray drift is impossible, problems can be significantly reduced by awareness of the major factors that cause drift, while taking precautions to minimize their influence on off-target movement of droplets. The nozzle you select and the weather conditions at the time of spraying are the two most influential factors affecting generating as well as reducing spray drift. Keep nozzles as close to the target as possible while still producing a uniform distribution of spray on the target. If weather conditions (wind speed and direction, humidity, temperature, inversions) are not favorable, and there is concern about spray that might result in drift, wait until there is no longer that element of doubt. Extensive information related to factors influencing spray drift, is in OSU Extension publication FABE-525. “Effect of Major Variables on Drift Distances of Spray Droplets.” (ohioline.osu.edu/factsheet/fabe-525).
- Maximize pesticide deposit and coverage on the target which may be different part of the crop canopy. For example, when applying a fungicide to manage Fusarium head blight or “head scab,” on small grains, the target is the head, not the leaves. On the other hand, when spraying for soybean sclerotinia stem rot (white mold), the most critical area that needs to be treated with fungicides is where flowering takes place. Nozzle selection has a significant influence on whether or not the droplets reach the specific target location in the canopy. For example, the twin-pattern nozzles or a single flat-fan nozzle tilted at a forward angle of 30 to 45 degrees down from the horizontal is definitely best for the application of fungicides for wheat head scab. It is, however, the worst setup for soybean insects and diseases, such as aphids and white mold, respectively.
- Slow down when spraying. Spray coverage is usually improved at slower speeds. The higher the travel speed, the greater likelihood of spray drift.
- Calibrate the sprayer. A sprayer can only be effective, efficient, and safe if properly checked and calibrated well before the sprayer is taken to the field, and periodically during the spraying season. Some may argue that most sprayers are now equipped with sophisticated rate controllers and ground speed sensors, and calibration is not necessary. Unfortunately, not all electronic controllers can detect flow rate changes on each nozzle on the boom, and none can detect changes in spray pattern. The primary goal with calibration is to determine the actual rate of application in gallons per acre, and then make adjustments if the difference between the actual rate and the intended rate is greater or less than 5% of the intended rate. There are several ways to calibrate a sprayer. One easy method is explained in the OSU Extension publication FABE-520, “Calibrating Boom Sprayers.” (ohioline.osu.edu/factsheet/fabe-520). Be safe. Wear protective clothing, goggles and rubber gloves, and respirators if required on the label, when calibrating the sprayer, doing the actual spraying, and cleaning the equipment.
- Check uniformity of application. How uniformly the chemical is deposited on the target is as important as the amount applied. Maintain uniform deposition of spray material on across the entire width of the target area. Non-uniform coverage results from using misaligned or clogged nozzles, using nozzles with different fan angles, or from uneven nozzle height across the boom. These common problems result in streaks, untreated areas, or over-application of chemicals.
- Understand how to calculate the amount of chemical product to mix in the tank. Although your sprayer may be in good condition and calibrated frequently, if the correct amount of chemical is not put into the tank, it can still result in unsatisfactory pest control. Detailed information on how to calculate the proper amount of chemical to add to the spray tank is provided in the OSU Extension publication FABE-530. “How Much Chemical Product Do I Need to Add to my Sprayer Tank.” (ohioline.osu.edu/factsheet/fabe-530).
- Take advantage of technological advancements in spray technology, such as GPS, automatic guidance systems, and independent control of nozzles using the PWM (Pulse Width Modulation). Update and upgrade your sprayer with these technologies that can be easily integrated in your existing sprayer.
- Consider using a sprayer that is equipped with air-assisted boom when coverage in lower parts of the canopy is essential for control of some insects and diseases especially under full, dense canopy conditions, such as soybeans sprayed in late season.
For more information on this topic, please read the OSU Extension publication FABE-532, “Best Practices for Effective and Efficient Pesticide Application.” (ohioline.osu.edu/factsheet/fabe-532). Don’t hesitate to contact me if you have a specific question that was not addressed in this and other OSU Extension publications I mentioned in this article.
Happy spraying!
-
Wet Weather then a Planting Window
April was a challenging month. It was a cold month with most of Ohio -1F to -3F below normal for temperatures. We saw late freezes and snow events. Because of the cold, precipitation was generally around or slightly below normal in the 60-120% of normal range. However, with limited evaporation and evapotranspiration, soils did not dry much.
Looking forward, May will start off challenging but improvements are forecasted. The first week of May will see a wetter period across Ohio with temperatures generally below normal. Rainfall will range from just under an inch to over 2 inches in places. As we move into the middle and end of May, expect a pattern change to warmer and drier than normal which should open the rapid window for planting.
It appears the chances for a hard freeze are pretty much over. There is still a low chance for some patchy frost especially in northern and eastern Ohio like this weekend but the freeze risk has decreased significantly.
The outlook for summer has not changed much from our last article. We expect slightly above normal temperatures this summer with the typical swings of dry to wet to dry on about a 30 day cycle. Overall, 2022 looks not as receptive to agriculture as it was in 2021 with a bit more of extreme periods including more intense dry and wet periods.
Rainfall totals through mid May will generally be 1-2 inches with isolated 3 inch totals in far western and northern areas as show in the image. You can get updated 16 day rainfall total maps at NOAA/NWS/OHRFC at: https://www.weather.gov/images/ohrfc/dynamic/NAEFS16.apcp.mean.total.png
You can also get the latest short-term evapotranspiration here: https://psl.noaa.gov/eddi/realtime_maps/images/latest.trim.png
The blue areas are short term wetness and the orange/brown areas are short-term rapid drought development so this tool is helpful in the summer.
-
Alfalfa Weevil: Ready, Set, Scout!
Finally we’ve accumulated enough heat units that significant parts of Ohio are now or very soon will be in prime time for alfalfa weevil. Peak larval activity and feeding damage occur between 325 and 575 GDD.
Accumulated growing degree days (base 48°F sine calculation method) for January 1-May2, 2022 at several CFAES Ag Weather System (https://www.oardc.ohio-state.edu/weather1/) locations and additional NOAA stations around Ohio (Midwestern Regional Climate Center (https://mrcc.purdue.edu).
In short, most locations should begin scouting, especially in fields that were damaged last fall by the fall armyworm, because we don’t want to add more insult to those fields early this season. Alfalfa fields should be scouted weekly for weevils until at least the first harvest. Follow-up scouting may be needed after the first harvest in heavily infested fields.
Spot problem fields early by checking alfalfa tips for feeding damage – small holes and a tattered appearance. Fields that have a south facing slope tend to warm up sooner and need to be checked for weevil earlier.
Here is a video about scouting weevils in alfalfa:
Scout for alfalfa weevils by collecting a series of 10 stem samples from various locations. Place the stems tip down in a bucket. After you’ve collected 10 stems, shake the stems vigorously into the bucket and count the larvae. Divide this number by 10 to get the average number of larvae per stem. Do this procedure at least 3 times (for a grand total of 30 stems, in 10-stem units). Alfalfa weevil larvae go through four growth stages (called instars). The shaking will dislodge the late 3rd and 4th instar larvae which cause most of the foliar injury. Close inspection of the stem tips may be needed to detect the early 1st and 2nd instar larvae. Also record the overall height of the alfalfa.
The treatment threshold is based on the number of larvae per stem, the size of the larvae and the height of the alfalfa according to the following table. When alfalfa is around 12-16 inches in height, growers can consider an early harvest rather than spraying, if they feel the current growth is sufficient to justify the cost of harvest or if spraying can’t be done for some reason (e.g., organic production). When alfalfa stem height is over 16 inches, we would always recommend an early cutting. In those fields which are cut early for alfalfa weevil, the regrowth should be checked closely to make sure weevils that are still alive do not prevent good regrowth.
Green alfalfa weevil larvae (the main feeding stage) at various growth stages, and brown adults. Photo by Julie Peterson, University of Nebraska.
Table 1. Action thresholds relevant to stand height, tip feeding, and density of larvae per stem.
Stand Height Inches
Indication of Problem % Tip Feeding
Problem Confirmation Larvae per Stem
Recommended Action
6
25
1
Recheck in 7 days
9
50
> 1
Spray
12
75
> 2
Spray
16
100
> 4
Harvest early
When harvested early due to weevil, check within one week for regrowth.
For more information about alfalfa weevil, visit our factsheet at https://ohioline.osu.edu/factsheet/ENT-32 If you are interested in a more detailed treatment of how growing degree days can be used in management decisions for alfalfa weevil, visit this website from the University of Kentucky https://entomology.ca.uky.edu/ef127
-
CFAES Ag Weather System 2022 Near-Surface Air and Soil Temperatures/Moisture (Update 5)
After last weekend’s summer preview, temperatures were much cooler over Ohio for much of the past week. Central and northern Ohio locations saw air temperatures drop below freezing mid-week, before a return to normal conditions over the weekend. Soil temperatures responded similarly, with two- and four-inch temperatures dropping back into the upper 40s to mid-50s before rebounding back into the mid to upper 50s toward the end of the weekend (Figure 1).
Figure 1: Daily average air temperature (dashed red), two-inch (green) and four-inch (blue) soil temperatures for spring 2022. Current daily average soil temperatures are noted for each location. Soil type and location of measurements (under sod or bare soil) are provided in the lower right corner of each panel. A map of all locations is in the bottom right. Data provided by the College of Food, Agricultural, and Environmental Sciences (CFAES) Agricultural Research Stations located throughout the state.
Figure 2: (Left) Percent of normal precipitation for April 19 – May 2, 2022. Figure provided by the Midwestern Regional Climate Center. (Right) Calculated soil moisture percentiles as of 05/01/2022 according to the Climate Prediction Center.
Figure 2 (left) shows that precipitation over the last two weeks has been below average for most of Ohio, despite the frequent light rain showers. The driest areas have been across central and southwest Ohio. This has provided soils a good opportunity to dry out with decent conditions noted across much of the state (Fig. 2- right). However, the forecast calls for several rounds of showers and storms this week. The Weather Prediction Center is calling for just under 1” to 2” of rain over the next 7 days.
The May 2nd Ohio Crop Progress Report (https://go.osu.edu/cropprogress) should show limited planting occurred for the week ending April 29th. These April planted fields will be closely watched for emergence. Germination progress is soil temperature and moisture-related. The temperature relationship is reasonably predictable for corn, requiring 100 to 120 growing degree days (GDDs) to emerge. We refer you to a 2021 CORN for more on calendar vs. GDD for corn emergence at https://go.osu.edu/cornemergence. Table 1 below shows accumulated GDD at CFAES weather stations since April 23rd, when fieldwork broadly began across the state. 2-inch soil temperatures from the CFAES network are used to generate GDD.
Table 1. GDD Accumulation at CFAES weather Stations based on 2-inch soil temperatures since April 23rd
CFAES Weather Station
GDD 2-in Soil
April 23 to May 1
Emergence (Yes or No)
1-Ashtabula
54
No
2-Northwest
26
No
3-North Central
40
No
4-Wooster
34
No
5-Western
73
No
6-Eastern
83
No
7-Piketon
80
No
For more complete weather records for CFAES research stations, including temperature, precipitation, growing degree days, and other useful weather observations, please visit https://www.oardc.ohio-state.edu/weather1/.
-
Lep Monitoring Network Update
Eleven counties in Ohio will be monitoring for various agronomic Lepidopteran (moth/caterpillar) pests during the 2022 field season. These counties include Adams, Brown, Clark, Fulton, Hardin, Madison, Muskingum, Trumbull, Van Wert, Wayne and Wood. This network was established to monitor the current pest populations in various regions of Ohio for black cutworm (BCW), true armyworm (AMW), European corn borer (ECB-IA, ECB-NY), corn earworm (CEW), and fall armyworm (FAW). We will report regular updates on this trapping in CFAES’s C.O.R.N newsletter to track the status of these pests in Ohio. Traps for each pest will be deployed when the pest is most likely to be active throughout the season.
Black cutworm
The first pest we are monitoring for this spring is the black cutworm (BCW). Black cutworms are not able to overwinter in Ohio--they migrate from southern regions as the temperatures begin to increase. Adult moths are particularly attracted to fields with broadleaf weeds, such as chickweed and purple dead nettle, to lay their eggs on before planting (Figures 1 and 2). Once the eggs hatch, the caterpillars feed on the corn seedlings or growing corn plants, and potentially cutting the plant off at the growing point.
April temperatures have been low but are slowly starting to increase. Understanding BCW numbers before planting will help identify regions that may be at increased risk for BCW. To monitor for BCW moths, our network of cooperators use wing traps with a pheromone lure (Figure 3). Black cutworm adults are a brownish color and can be identified by a single dagger shape on each forewing (Figure 4).
Traps were set the week of April 18th and we started weekly checks beginning the week of April 25th. Over the past week, we monitored a total of 24 traps in 9 counties. Moths were reported in all monitoring counties except Brown (Figure 5). Van Wert, Wood and Trumbull counties had the highest averages the first week (7, 6 and 6 moths, respectively). Counties with high trap numbers should plan to monitor for BCW larvae after corn is planted, especially in fields with a lot of broadleaf weeds such broadleaf weeds, such as chickweed and purple dead nettle. For more information about BCW please visit: https://aginsects.osu.edu/sites/aginsects/files/imce/ENT_35_14%20BCW.pdf
Black cutworm moth report
Week 1: April 25 to May 1, 2022
For corn varieties tolerant of BCW, please review the Handy Bt Trait Table: https://aginsects.osu.edu/bt-corn-trait-table
-
Making On-Farm Trials Easy
Planting season is upon us and is a little behind in comparison to last year. Many producers are planning on evaluating input costs and management practices on their farm this season to improve economic efficiency and stay profitable. However, there are some ways to plan on-farm research to get the most accurate data, and therefore make the best decision for your farm.
The first element to establish is what are you trying to find out? Fully understanding the question and goal of the trial is imperative to set up the appropriate treatments. Maybe your question is “What is my most economically effective nitrogen rate?” or “Does this new fungicide increase yield and pay for itself?”. When doing on farm research, consider assessing practices that are critical to the long-term success of the farm.
Once your question is determined, set up the treatments that you desire to observe. This is generally a comparison of your nontreated control or “common practice”, and the new practice or product. For trials that are assessing seeding rates and fertilizer rates, more than two treatments are necessary to determine the optimal rate.
The most important keys for effective research are replication and randomization. A replication is a repetition of a group of treatments and randomization is choosing at random the pattern of the treatments within replications. Both of these elements are important to reduce the effect of field variability skewing results, increase confidence in your data collection, and provides more data throughout the field. Many farmers split the field in half to compare treatments, however this does not account for soil type changes, low spots, hills, etc. Randomization is especially needed to ensure that one treatment is not unknowingly favored over another. We require at least 3 replications and encourage using 4. The digital ag team has some pre-designed layouts in eFields that can be used to build your own study from, and can be found at this link https://digitalag.osu.edu/efields/get-involved/study-implementation.
To make your on-farm research process easier, remember to evaluate your equipment and know how many planter passes are needed for the header to collect data. If using more than one pass, taking the combine through the center of two passes can also eliminate treatment carryover, especially in a fungicide or fertilizer treatment. To measure yield accurately use either a weigh wagon, a grain cart with scales, or a calibrated yield monitor.
The information that is collected from on-Farm trials done with Extension educators can be published in our eFields annual report, show casing on-Farm research done throughout the state, giving producers and educators a platform to share their information.
-
It’s Time to Start Monitoring your Alfalfa Fields for %NDF
Ohio has seen on average a cooler spring than in previous years even though there were record and near-record highs last month. Fluctuations in temperature and varying rainfall make it extremely difficult to determine the exact date every year when to harvest alfalfa stands. If managed properly, spring harvests can be one of our most and least digestible harvest of the year. Many growers may base harvest decisions primarily on alfalfa maturity; however, this method can be misleading due to climatic variations affecting the rate of bud and flower development.
Spring changes of alfalfa %NDF can increase about 5 percentage units each week. Therefore, it is imperative for growers to be monitoring their alfalfa for optimal harvest times. Traditional wet chemistry remains the best method to measure %NDF; however, these traditional methods are often too time consuming when a rapid estimation of NDF is needed to make harvest decisions.
Growers can easily measure %NDF in their fields using a method referred to as PEAQ, Predictive Equations for Alfalfa Quality. This method uses max height and max stage of a pure standing alfalfa crop to determine %NDF. Neutral Detergent Fiber estimations using this method can begin as soon as the alfalfa crop reaches at least 16 inches in height. The protocol for utilizing PEAQ in the fields can be found here and short video describing the method can also be found here.
The PEAQ method was developed for pure alfalfa stands. Using this method to determine %NDF of alfalfa-grass mixtures will be inaccurate. Cornell University has developed a method to estimate %NDF in both grass and alfalfa-grass mixtures using a smart phone app. More information on this method and where to download the app can be found at forages.org.
Over the next few weeks ANR Educators and State Specialists across Ohio will be reporting %NDF of pure alfalfa stands. Below are NDF estimates from the past week.
Table 1. Alfalfa Average %NDF for Counties Across Ohio
Date
Location (County)
Average Height
Stage
Average %NDF
4/25/22
Adams
17.7
Vegetative
29.7
4/29/22
Adams
18.6
Vegetative
30.7
4/30/22
*Geauga
8
Vegetative
5/2/22
Licking
16
Vegetative
28.6
4/29/22
*Putnam
12
Vegetative
4/29/22
*Stark
12
Vegetative
5/2/22
*Wayne
12
Vegetative
* Alfalfa with max height below 16 inches cannot be calculated using PEAQ.
The Hay and Forage Grower recently published a great article on the importance of a timely first cutting alfalfa harvest. This article can be found here.
Crop Observation and Recommendation Network
C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.
Contributors
Disclaimer
The information presented here, along with any trade names used, is supplied with the understanding that no discrimination is intended and no endorsement is made by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.
CFAES provides research and related educational programs to clientele on a nondiscriminatory basis. For an accessible format of this publication, visit cfaes.osu.edu/accessibility.